Field of the Invention
The present invention relates to a secondary fuel injection system and method for diesel engines which increases power/torque output of the diesel engines per unit of fuel across the widest possible range of engine operating conditions, and which correspondingly achieves other related benefits, including reductions in fuel consumption, reductions in undesirable engine emissions, and extended engine life. More particularly, the present invention pertains to such a secondary fuel injection system and method which achieves a substantial increase in power output of a diesel engine per unit of fuel across the widest possible range of engine operating conditions by supplementing diesel fuel that is directly injected into the engine cylinders with one or more oxygen-containing secondary fuels, such as ethanol or E85, that is/are drawn into the cylinders with air via the engine's intake system so as to achieve more complete combustion of all fuels within the cylinders. Additionally, the system and method can be implemented efficiently and economically with a minimal number of parts and closed-loop control using data pertaining to engine operations, operations of a vehicle or other machine on which the engine is installed (chassis and other system sensors), and the like, which is available from standard sensors provided with the engines and with the vehicles or other machines.
Description of the Background Art
There are many known systems and methods involving use of secondary fuel(s) for improving performance of diesel engines. These include U.S. Pat. No. 4,424,676 (Meiners), U.S. Pat. No. 4,553,504 (Duggal et al.) U.S. Pat. No. 4,958,598 (Fosseen), U.S. Pat. No. 4,876,988 (Paul et al.), U.S. Pat. No. 7,225,763 (Ritter et al.), U.S. Pat. Nos. 7,284,506 and 7,409,926 (Sun et al.), U.S. Pat. No. 7,921,833 (Bidner et al.), U.S. Pat. No. 8,616,177 (Reitz), US Published Application No. 2004/0103859 A1 (Shetley), US Published Application No. 2007/0131180 A1 (Roehm), and US Published Application No. 2014/0026853 A1 (Gray et al.).
While such other known systems and methods disclose various considerations which may be important for achieving desired operational performance from a diesel engine through use of secondary fuel(s), as well as various theories relating to such considerations, none of the known systems and methods are capable of achieving a significant increase in power output of a diesel engine per unit of fuel across a wide range of engine operating conditions. Further, the known systems and methods often require special equipment, sensors, complex operations, etc., making them unduly expensive and/or complex.
Thus, while there are known systems and methods involving use of secondary fuel(s) for diesel engines, there remains a need in the art for achieving increased power/torque across the widest possible range of engine operating conditions, and which can be implemented efficiently and economically. It is an object of the present invention to fill such need.